Magnetic Sensor Packaging for Transmissions

ABSTRACT

Designs to package a magneto-elastic torque sensor in an automotive transmission for volume production applications are provided. A transfer case assembly includes a transfer case shaft having a magnetized region and a magnetic torque sensor, for detecting torque of the transfer case shaft, mounted on at least one bushing supporting the transfer case shaft. A drive axle assembly includes an axle housing, an input shaft having a magnetized region, and a magnetic torque sensor, for detecting torque of the input shaft, mounted to the axle housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/016,654, filed Feb. 5, 2016, now U.S. Pat. No. ______; which is adivisional of U.S. application Ser. No. 13/771,258, filed Feb. 20, 2013,now U.S. Pat. No. 9,285,282; the disclosures of which are herebyincorporated in its entirety by reference herein.

TECHNICAL FIELD

The present invention relates to automatic transmissions having magneticsensors.

BACKGROUND

An automatic transmission of a vehicle includes an input shaft and anoutput shaft. The input shaft receives an input torque at an input speedfrom power derived from a power source such as an engine. Thetransmission converts the input torque at the input speed to an outputtorque at an output speed. The output shaft transmits the output torqueat the output speed to traction wheels of the vehicle in order to propelthe vehicle.

The transmission converts the input torque at the input speed to theoutput torque at the output speed by adjusting a gear ratio (forexample, during an up-shift or down-shift) between the input and outputshafts. The transmission shifting is accomplished by applying and/orreleasing friction elements (such as clutches, band-brakes, etc.) tochange speed and torque relationships by altering planetary gearconfigurations of the transmission. As a result, power flow paths areestablished and disestablished from the engine to the wheels.

The friction elements must be properly controlled in order tosatisfactorily shift the transmission. To this end, informationregarding the operation of the transmission is used to control thefriction elements. For instance, information indicative of the inputtorque received by the input shaft and the speed of the input shaft andinformation such as vehicle speed and throttle opening may be used.Similarly, information indicative of the output torque transmitted bythe output shaft and the speed of the output shaft may be used.

Torque and speed of the input shaft and the output shaft are typicallyestimated based on various type of available information. One way toavoid estimation is to use a magnetic sensor mounted within thetransmission to directly detect the torque and/or speed parameters.However, installation and packaging of such magnetic sensors withinlimited spaces of the transmission may provide a challenge.

SUMMARY

Embodiments of the present invention are directed to designs forpackaging magnetic sensors such as magneto-elastic torque sensors inautomatic transmissions for volume production.

In one embodiment, the present invention provides a transmission havingan output shaft and a magnetic torque sensor. The output shaft has amagnetized region. The sensor, for detecting torque of the output shaft,is mounted on at least one friction reduction member such as a bushingsupporting the output shaft.

In one embodiment, the present invention provides a transmission havinga transmission case, an output shaft, and a magnetic torque sensor. Theoutput shaft has a magnetized region. The sensor, for detecting torqueof the output shaft, is mounted to the transmission case.

In one embodiment, the present invention provides a transmissionincluding a stator tube and a magnetic torque sensor. The stator tubeencompasses an input shaft having a magnetized region. The stator tubehas a window adjacent the magnetized region. The sensor, for detectingtorque of the input shaft, is positioned within the window and affixedto the stator tube to be adjacent the magnetized region.

In one embodiment, the present invention provides a transmissionincluding a transmission case, a gear having a magnetized region, and amagnetic torque sensor. The gear is one of an idler gear and a transfergear. The sensor, for detecting torque of the output shaft, is mountedto the transmission case.

In one embodiment, the present invention provides a transmissionincluding a transmission case, a hollow idler shaft having a magnetizedregion on an inner surface thereof, and a magnetic torque sensor. Thesensor, for detecting torque of the idler shaft, is positioned withinthe idler shaft and mounted to the transmission case.

In one embodiment, the present invention provides a transmissionincluding a transmission case, a differential drive carrier having amagnetized region, and a magnetic torque sensor. The sensor, fordetecting torque of the driver carrier, is mounted to the transmissioncase.

In one embodiment, the present invention provides a transmissionincluding a transmission case, at least one half-shaft having amagnetized region, and a magnetic torque sensor. The sensor, fordetecting torque of the at least one half-shaft, is mounted on thetransmission case.

In one embodiment, the present invention provides a transmissionincluding a transmission case, an idler shaft, an idler gear, a transfergear, and a magnetic torque sensor. The gears are spaced apart from oneanother about different portions of the idler shaft. The idler shaftincludes a magnetized region in the space between the idler gear and thetransfer gear. The sensor, for detecting torque of the idler shaft, ismounted on the transmission case adjacent to the magnetized region.

In one embodiment, the present invention provides a transfer caseassembly. The assembly includes a transfer case shaft and a magnetictorque sensor. The transfer case shaft has a magnetized region. Thesensor, for detecting torque of the transfer case shaft, is mounted onat least one friction reduction member such as a bushing supporting thetransfer case shaft.

In one embodiment, the present invention provides a rear-wheel driveaxle assembly having a rear-axle housing, an input shaft having amagnetized region, and a magnetic torque sensor. The sensor, fordetecting torque of the input shaft, is mounted to the rear-axlehousing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a vehicle powertrain in accordancewith embodiments of the present invention;

FIG. 2 illustrates a cross-sectional view of the torque converter andthe transmission of the powertrain shown in FIG. 1 in which thetransmission lacks both of an input shaft sensor and an output shaftsensor;

FIGS. 3A, 3B, and 3C illustrate an example of a magnetic torque sensorfor detecting torque of a shaft;

FIG. 4 illustrates an example of a magnetic speed sensor for detectingrotating speed of a shaft;

FIG. 5 illustrates a cross-sectional view of an automatic transmissionhaving an output shaft mounted magnetic torque sensor packaging designin accordance with an embodiment of the present invention;

FIG. 6 illustrates a cross-sectional view of an automatic transmissionhaving a case-mounted with press fit magnetic torque sensor packagingdesign in accordance with an embodiment of the present invention;

FIG. 7 illustrates a cross-sectional view of the input shaft area of afront wheel drive transmission in which the input shaft area lacks amagnetic torque sensor;

FIG. 8 illustrates a cross-sectional view of the input shaft area of thetransmission shown in FIG. 7 having an input shaft magnetic torquesensor packaging design in accordance with an embodiment of the presentinvention;

FIG. 9 illustrates a cross-sectional view of the output shaft area ofthe transmission shown in FIG. 7 in which the output shaft area lacks amagnetic torque sensor;

FIG. 10 illustrates a cross-sectional view of the output shaft area ofthe transmission shown in FIG. 7 having an idler gear magnetic torquesensor packaging design in accordance with an embodiment of the presentinvention;

FIG. 11 illustrates a cross-sectional view of the output shaft area ofthe transmission shown in FIG. 7 having an idler gear shaft magnetictorque sensor packaging design in accordance with an embodiment of thepresent invention;

FIG. 12 illustrates a cross-sectional view of the output shaft area ofthe transmission shown in FIG. 7 having a differential hub magnetictorque sensor packaging design in accordance with an embodiment of thepresent invention;

FIG. 13 illustrates a cross-sectional view of the output shaft area ofthe transmission shown in FIG. 7 having a half-shaft magnetic torquesensor packaging design in accordance with an embodiment of the presentinvention;

FIG. 14 illustrates a cross-sectional view of the input shaft area ofanother front wheel drive transmission in which the input shaft arealacks a magnetic torque sensor;

FIG. 15 illustrates a cross-sectional view of the input shaft area ofthe transmission shown in FIG. 14 having an input shaft magnetic torquesensor packaging design in accordance with an embodiment of the presentinvention;

FIG. 16 illustrates a cross-sectional view of a rear wheel drivetransfer case with all-wheel drive (AWD) in which the transfer caselacks a magnetic torque sensor;

FIG. 17 illustrates a cross-sectional view of the transfer case shown inFIG. 16 having a shaft-mounted magnetic torque sensor packaging designin accordance with an embodiment of the present invention;

FIG. 18 illustrates a cross-sectional view of the transfer case shown inFIG. 16 having a case-mounted magnetic torque sensor packaging design inaccordance with an embodiment of the present invention; and

FIG. 19A illustrates a cross-sectional view of a magnetic torque sensorpackaging design in a rear-wheel drive (RWD) axle in accordance with anembodiment of the present invention;

FIG. 19B illustrates an enlarged view of the encircled portion of FIG.19A.

DETAILED DESCRIPTION

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely exemplary of the invention that may be embodied in various andalternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

Referring now to FIG. 1, a block diagram of a vehicle powertrain 10 inaccordance with embodiments of the present invention is shown.Powertrain 10 includes an engine 12, a torque converter 14, and anautomatic transmission 16. Transmission 16 has an input shaft 18 and anoutput shaft 20. Engine 12 delivers torque to torque converter 14 viacrankshaft 13 of engine 12 which is connected to torque converter 14.Torque converter 14 converts the engine torque into an input torque atan input speed and transmits the input torque at the input speed toinput shaft 18 of transmission 16. Transmission 16 serves to change atransmission ratio and thus changes the input torque at the input speedinto an output torque (for example, increased torque) at an output speed(for example, reduced speed). Transmission 16 transmits the outputtorque at the output speed to output shaft 20. Output shaft 20 isconnected to a vehicle driveline (not shown) such that the output torqueat the output speed may be used to drive wheels of the vehicle.

While not shown herein, embodiments of the present invention can be usedas well in a hybrid powertrain that includes, for example, an engine andan electric motor without a torque converter.

Powertrain 10 further includes at least one of an input shaft sensor 22and an output shaft sensor 24. Input shaft sensor 22 is associated withinput shaft 18 and is configured to monitor at least one of (input)torque and (input) speed of input shaft 18. Similarly, output shaftsensor 24 is associated with output shaft 20 and is configured tomonitor at least one of (output) torque and (output) speed of outputshaft 20. Sensors 22 and 24 provide sensor signals indicative of themonitored information to a controller (not shown) for the controller tocontrol operation of transmission 16 accordingly.

Referring now to FIG. 2, with continual reference to FIG. 1, across-sectional view of torque converter 14 and transmission 16 isshown. As shown in FIG. 2, torque converter 14 is encased within atorque converter case 26 and transmission 16 is encased within atransmission case 28.

Transmission mechanism 30 changes the input torque at the input speedreceived by input shaft 18 into an output torque at an output speedtransmitted by output shaft 20. As illustrated in the right-hand side ofFIG. 2, transmission mechanism 30 uses planetary gear sets. Embodimentsof the present invention may be applied to other types of transmissionmechanisms including, but not limited to, belt-drive transmissions, dualclutch transmissions, or continuously variable transmissions.

Torque converter 14 includes a turbine 32, a stator 34, and an impeller36. Impeller 36 is fixedly connected to engine crankshaft 13 such thatimpeller 36 rotates as crankshaft 13 rotates. Stator 34 is fixed ontothe stator shaft (i.e., the stator tube) of a stator support 40 via aone-way clutch 39. Stator support 40 is fixed to transmission case 28.Turbine 32 is mechanically linked via a turbine hub 42 to input shaft18.

Notably, transmission 16, as shown in FIG. 2, does not have either aninput shaft sensor 22 for directly measuring torque and/or speed ofinput shaft 18 or an output shaft sensor 24 for directly measuringtorque and/or speed of output shaft 20.

In accordance with embodiments of the present invention, a transmissionis configured with inventive design concepts and features for enablingthe packaging of an input shaft sensor 22 and/or an output shaft sensor24 within the transmission in which sensors 22 and 24 are magneticsensors. The packaging of an input shaft sensor 22 within a transmissionin accordance with embodiments of the present invention enables directmeasurement of torque and/or speed of input shaft 18. Similarly, thepackaging of an output shaft sensor 24 within a transmission inaccordance with embodiments of the present invention enables directmeasurement of torque and/or speed of output shaft 20.

In some embodiments, sensors 22 and 24 are magnetic torque sensors formonitoring torque of input and output shafts 18 and 20, respectively.Similarly, in some embodiments, sensors 22 and 24 are magnetic speedsensors for monitoring speed of shafts 18 and 20, respectively. Further,in some embodiments, sensors 22 and 24 are magnetic torque and speedsensors for monitoring torque and speed of shafts 18 and 20,respectively.

Magnetic torque and speed sensor technology operates optimally with afree smooth surface area on a shaft with constant diameter andcontrolled hardness, wherein a part of the shaft is magnetized. Themagnetic sensor technology makes use of magnetic flux sensing elementssuch as fluxgate sensors. The sensing elements are preferably stationaryand fixed with respect to the rotating magnetized surface of the shaft.Translation of the shaft in either the axial or radial directionrelative to the sensor housing is preferably minimized. As indicatedabove, conventional transmission designs, such as shown in FIG. 2, mayrepresent a challenge for packaging of magnetic sensors.

Sensors 22 and 24 may be magneto-elastic sensors as described in U.S.Pat. Nos. 6,145,387; 6,047,605; 6,553,847; and 6,490,934. Other magneticsensors may also be used to enable accurate measurements of torqueexerted onto a rotating shaft and rotating speed of the shaft withoutphysical contact between a magnetic flux sensing element of the sensorand the shaft.

Referring now to FIGS. 3A, 3B, and 3C, an example of a magnetic torquesensor for detecting torque of a shaft will be described. This exampleassumes that the shaft is input shaft 18 and that the magnetic torquesensor is input shaft sensor 22.

Input shaft sensor 22 includes a magnetic flux sensing element(s) withina sensor housing 44. Input shaft 18 includes a magnetized region 46.Magnetized region 46 circumferentially extends around input shaft 18.Magnetized region 46 may be created by coating magnetized material as athin layer on a chosen region of input shaft 18 or by magnetizing aregion on the shaft. Sensor housing 44 is fixed in position adjacent tothe magnetized region 46 of input shaft 18 to enable the sensing elementto sense the torque induced signal.

Preferably, shaft 18 is made of steel having high Nickel content,preferably with Martensite structure at the surface layer. Shaft 18 ishardened to enable permanent magnetization. The chosen magnetized region46 of shaft 18 is magnetized with magnetized material thereon to adesigned depth from the surface within the hardened layer. A magneticpattern or polarity signature may depend on a certain implementation ofmagneto-elastic torque sensing principles. However, they require amagnetized region 46 of shaft 18 and a sensor housing 44 that containsone or more magnetic flux sensing elements. Sensor housing 44 mayinclude other types of sensing elements such as thermo-couples.

At no load (FIG. 3A), magnetic flux 47 is contained near or within theshaft surface. The illustration in FIG. 3A shows a simplified view offlux direction. Depending on chosen magnetization patterns, magneticflux may have more complex directional patterns.

When load is applied (i.e., input shaft 18 is twisted), magnetic flux 47extends from the shaft surface and its axial component which isproportional to the applied torque is measured by the sensing element(FIGS. 3B and 3C). For instance, as shown in FIGS. 3B and 3C, magneticflux 47 is realigned in one direction when the load is greater than zeroand is realigned in the opposite direction when the load is less thanzero. Either realignment causes more magnetic flux 47 to come out fromthe shaft surface in proportion to the load level. As indicated in FIGS.3B and 3C, the sensing element detects the magnetic flux direction andintensity. Variations of this technology may include, for example, dualband and tri-band magneto-elastic torque sensors.

Referring now to FIG. 4, an example of a magnetic speed sensor fordetecting rotating speed of a shaft will be described. Again, thisexample assumes that the shaft is input shaft 18 and that the magneticspeed sensor is input shaft sensor 22. Input shaft sensor 22 includessensor housing 44 having magnetic flux sensing element(s). Input shaft18 includes a magnetized region 48 comprised of magnetic material placedin spots repeatedly around the circumference of input shaft 18 as shownin FIG. 4. Sensor housing 44 is placed near the shaft surface, pickingup the circumferential component of magnetic flux. A periodic voltagesignal is generated on a magnetic spot as the rotating shaft 18 passesby the sensing element. The periodic voltage signal can be convertedinto a square wave signal using a comparator circuit which can then beconverted into rpm by counting the number of square wave periods.Variations of this technology may include, for example, single band anddual band speed sensors.

For simplicity, a magnetic torque and/or speed sensor is referred toherein as a “magnetic torque sensor” or simply “sensor”. However, asdescribed above, such a magnetic torque sensor or sensor may be amagnetic torque sensor only, a magnetic speed sensor only, or a magnetictorque and speed sensor.

With the foregoing description in mind, various embodiments of thepresent invention will now be described.

With reference to FIGS. 5 and 6, embodiments of the present inventionprovide unique packaging layouts of a magnetic torque sensor for theoutput shaft of a transmission.

Referring now to FIG. 5, a cross-sectional view of an automatictransmission 50 having an output shaft mounted magnetic torque sensorpackaging design in accordance with an embodiment of the presentinvention is shown. General features of this design include sensor 24being supported by friction reduction members such as bearings orbushings to maintain a fixed distance between sensing element 44 ofsensor 24 and output shaft 20. The axial and radial alignment of sensor24 is insensitive to relative motion between output shaft 20 andtransmission case 28. An additional axial length is used for thebearings and an anti-rotation device is included.

Particular features, as shown in FIG. 5, of this design include thefollowing. The housing of sensor 24 is mounted on bearings or bushingssupporting output shaft 20 as indicated at 51. An anti-rotation devicefor the housing of sensor 24 can be positioned in several ways. In oneway, as indicated at 52, a slot is cut into transmission case 28 and akey is molded to the outside of the sensor housing. A snap ring ensuresaxial location of sensor 24 relative to output shaft 20 as indicated at53. The relative diameters of the bearings, sensor 24, the anti-rotationdevice, and a seal ensure assembly-feasibility as indicated at 54.Sensor 24 is protected from dust since it is sitting inboard of the sealas indicated at 55. A lubrication hole ensures wetting of sensorysurface on output shaft 20 and provides passage to lubricate othercomponents (bearing, seal) as indicated at 56. Wiring of sensor 24 isrouted internally through transmission case 28 to a common power andcontrol bus (not shown) as indicated at 57 a. Alternatively, wiring ofsensor 24 is routed externally through a seal, preferably near the topof transmission case 28, as indicated at 57 b. A common transmissioncase 28, sensor housing, and snap ring can be used for both 4×4 and 4×2versions as indicated at 58 (4×4 version shown above centerline and 4×2version shown below centerline).

Referring now to FIG. 6, a cross-sectional view of an automatictransmission 60 having a case-mounted with press fit magnetic torquesensor packaging design in accordance with an embodiment of the presentinvention is shown. General features of this design include thefollowing. The sensor housing functions as an anti-rotation device andthere is no need for sensor bearings of bushings.

Particular features, as shown in FIG. 6, of the design include thefollowing. The sensor housing is mounted to transmission case 28 bypress fit as indicated at 61. As such, the press-fitted sensor housingfunctions as an anti-rotation device and a snap ring for axialpositioning of sensor 24 is not required. The relative diameters of thebearings, sensor 24, and the seal ensure assembly-feasibility asindicated at 62. Sensor 24 is protected from dust since it is sittinginboard of the seal (in both 4×2 and 4×4 versions) as indicated at 63.In the 4×4 version (above the centerline), the seal is integrated intothe sensor housing. A lubrication hole ensures wetting of sensorysurface on output shaft 20 and provides passage to lubricate othercomponents (bearing, seal) as indicated at 64. Wiring of sensor 24 isrouted internally through transmission case 28 to a common control busas indicated at 65 a. Alternatively, wiring of sensor 24 is routedexternally through a seal, preferably near the top of transmission case28 as indicated at 65 b. A common transmission case 28 and sensorhousing can be used for both 4×4 and 4×2 versions as indicated at 66.

It is briefly noted that the principles of packaging designs inaccordance with embodiments of the present invention, as well as theprinciples of other packaging designs described herein, can be appliedto various power-train components including the transfer case, theengine crankshaft, the power take-off shaft, etc.

With reference to FIGS. 7 through 13, embodiments of the presentinvention provide unique packaging layouts of magnetic torque sensorsfor a front wheel drive transmission.

Referring now to FIG. 7, a cross-sectional view of the input shaft areaof a front wheel drive transmission 70 in which the input shaft arealacks a magnetic torque sensor is shown. For simplicity, the samereference numerals used above will be used for like components oftransmission 70 as is shown in FIG. 7 and as modified in accordance withembodiments of the present invention as described below.

Referring now to FIG. 8, a cross-sectional view of the input shaft areaof transmission 70 shown in FIG. 7 having an input shaft magnetic torquesensor packaging design 90 in accordance with an embodiment of thepresent invention is shown. As shown in FIG. 8, features of design 90include a shortened spline as indicated at 91. Slots are cut into statorsupport 40 and sleeve (at one and seven o'clock positions) (six o'clockposition is just for better illustration) as indicated at 92. A filletis provided to avoid damaging the bushing as indicated at 93. The PCboard enclosure of a sensor 22 is fixed by screws as indicated at 94.The PC board enclosure should not be leak-proof and should withstand 120psi and oil temperatures of 200 F to 250 F. The pressure blow off valveis set at 165 psi and heavy towing can impinge 300 F. The ID of thesleeve is changed to the same as the ID of stator support 40 asindicated at 95. The sleeve is pressed in after the wiring of sensor 22is routed. A groove is milled circumferentially for the wiring asindicated at 96. A groove is milled to feed the wiring through the applypressure port of torque converter 14 as indicated at 97. Holes aredrilled for the wiring at ten o'clock (twelve o'clock position is justfor better illustration) as indicated at 98. The wiring is glued and/orsealed in place as further indicated at 98. Grooves are milled for thewiring as indicated at 99. The wiring is routed to a connector attransmission case 28 as indicated at 99 a.

Referring now to FIG. 9, a cross-sectional view of the output shaft areaof transmission 70 shown in FIG. 7 in which the output shaft area lacksa magnetic torque sensor is shown. As indicated in FIG. 9, potentiallocations for a magnetic torque sensor include: sensor at gear face(idler gear magnetic torque sensor packaging design—FIG. 10) asindicated at 101; sensor on shaft internal diameter (idler gear shaftmagnetic torque sensor packaging design—FIG. 11) as indicated at 102;sensor on differential drive carrier (differential hub magnetic torquesensor packaging design—FIG. 12) as indicated at 103; and sensor onhalf-shaft (half-shaft magnetic torque sensor packaging design—FIG. 13)as indicated at 104.

Referring now to FIG. 10, with continual reference to FIG. 9, across-sectional view of the output shaft area of transmission 70 shownin FIG. 7 having an idler gear magnetic torque sensor packaging design110 in accordance with an embodiment of the present invention is shown.Features of design 110 include the following. A portion of either anidler gear or a transfer gear is magnetized on its surface to produce amagnetic sensing region as indicated at 111. The sensing element ofmagnetic torque sensor 24 is mounted into transmission case 28 orbulkhead adjacent to the magnetized surface of the idler gear asindicated at 112.

Referring now to FIG. 11, with continual reference to FIG. 9, across-sectional view of the output shaft area of transmission 70 shownin FIG. 7 having an idler gear shaft magnetic torque sensor packagingdesign 120 in accordance with an embodiment of the present invention isshown. Features of design 120 include the following. The gear of thedifferential drive is flipped onto the left side as indicated at 121(for instance, compare with FIG. 9). The gear of the idler shaft, theparking gear, and the bearing are moved to the left as indicated at 122.The features indicated at 122 further include reducing the parking geardiameter and making a corresponding minor change to transmission case28. A portion of the internal surface of the idler gear shaft ismagnetized to produce a magnetic sensing region as indicated at 123. Thesensing element of magnetic torque sensor 24 is mounted onto a sleeverunning through the internal diameter of the idler gear as indicated at124. Wiring of the sensing element is routed out through the sleeve asindicated at 125.

With continual reference to FIG. 11, in another variation the outersurface of a portion of the idler shaft between the transfer shaft inputgear and the transfer shaft output gear includes a magnetized region. Asensor is mounted to the case adjacent to the magnetized region to readthe torque of the idler shaft.

Referring now to FIG. 12, with continual reference to FIG. 9, across-sectional view of the output shaft area of transmission 70 shownin FIG. 7 having a differential hub magnetic torque sensor packagingdesign 130 in accordance with an embodiment of the present invention isshown. Features of design 130 include the following. The surface of thedifferential drive carrier is extended as indicated at 131. A portion ofthe carrier surface is magnetized as indicated at 132. The sensingelement of magnetic torque sensor 24 is mounted onto transmission case28 adjacent the magnetized carrier surface as indicated at 133. Wiringof the sensing element is routed out as indicated at 134. In anotherembodiment, the sensing element of magnetic torque sensor 24 is mountedonto transmission case 28 between the final drive (bevel) gear and theside carrier pin shaft and adjacent the magnetized carrier surface.

Referring now to FIG. 13, with continual reference to FIG. 9, across-sectional view of the output shaft area of transmission 70 shownin FIG. 7 having a half-shaft magnetic torque sensor packaging design140 in accordance with an embodiment of the present invention is shown.Design 140 is for FWD only. Features of design 140 include thefollowing. The half-shaft and the associated seal are moved axially awayfrom the transmission in both directions (i.e. to the left and to theright) as indicated at 141. This requires a change to transmission case28. The surfaces of half-shafts are magnetized in the manner describedabove as indicated at 142. The sensing elements of magnetic torquesensors 24 are mounted onto transmission case 28 adjacent the magnetizedsurfaces of the half-shafts, respectively, as indicated at 143. Wiringof the sensing elements is routed out as indicated at 144.

With reference to FIGS. 14 and 15, an embodiment of the presentinvention provides a unique packaging layout of a magnetic torque sensorfor input shaft of another front wheel drive transmission.

Referring now to FIG. 14, a cross-sectional view of the input shaft areaof a front wheel drive transmission 140 in which the input shaft arealacks a magnetic torque sensor is shown. For simplicity, the samereference numerals used above will be used for like components oftransmission 140 as is shown in FIG. 14 and as modified in accordancewith an embodiment of the present invention as described below.

Referring now to FIG. 15, a cross-sectional view of the input shaft areaof transmission 140 shown in FIG. 14 having an input shaft magnetictorque sensor packaging design 160 in accordance with an embodiment ofthe present invention is shown. In transmission 140, stator assembly 40is made of a stator support and a stator tube which press-fit togetherto form stator assembly 40. The assembled stator assembly 40 isinterconnected with a pump assembly by bolts in this design. As shown inFIG. 15, features of design 160 include the following. The outsidediameter of input shaft 18 is made straight as indicated at 161. Slots(windows) are cut in stator support 40 for the PC board and enclosure ofmagnetic torque sensor 22 as indicated at 162. A circumferential grooveis milled for the wiring of the sensing element of sensor 22 asindicated at 163. An axial groove is milled for the wiring as indicatedat 164. A hole is drilled for the wiring and the wiring is glued and/orsealed in place as indicated at 165. The wiring is routed out of thetransmission as indicated at 167.

With reference to FIGS. 16, 17, and 18, embodiments of the presentinvention provide unique packaging layouts of magnetic torque sensorsfor a rear wheel drive transfer case with all-wheel drive (AWD).

Referring now to FIG. 16, a cross-sectional view of a rear wheel drivetransfer case 170 in which transfer case 170 lacks a magnetic torquesensor is shown. For simplicity, the same reference numerals used abovewill be used for like components of transfer case 170 as is shown inFIG. 16 and as modified in accordance with embodiments of the presentinvention as described below.

As indicated in FIG. 16, potential first and second placement optionsfor a magnetic torque sensor include: sensor on the input shaft (largediameter, smooth outer surface) as indicated at 171; and sensor on theoutput shaft (small diameter, sensor linearity range may be reduced) asindicated at 172.

Referring now to FIG. 17, a cross-sectional view of transfer case 170shown in FIG. 16 having a shaft mounted magnetic torque sensor packagingdesign 180 in accordance with an embodiment of the present invention isshown. Design 180 includes the first and second placement optionsindicated above.

Features of design 180 pursuant to the first option in which a magnetictorque sensor 22 is on the input shaft include the following. Splinesare moved to the right (up to the pump's shoulder) to gain more axialspace for sensor 22 as indicated at 181. This modification is needed toboth of the input and output shafts. Sensor 22 is axially located at oneend by a shoulder on the input shaft as indicated at 182 a. Sensor 22 isaxially located at the other end by a snap ring as indicated at 183a.The housing of sensor 22 is supported by bearings as indicated at 184 a.An anti-rotation finger is provided as indicated at 185 a. Wiring of thesensing element of sensor 22 is routed out through a standard connectoras indicated at 186 a.

Features of design 180 pursuant to the second option in which a magnetictorque sensor 24 is on the output shaft include the following. Thediameter of the output shaft is increased as possible to avoid reductionin the linearity range of sensor 24 as indicated at 187. Sensor 24 isaxially located at one end by a washer as indicated at 188. Sensor 24 isaxially located at the other end by a snap ring as indicated at 183 b.The housing of sensor 24 is supported by bearings as indicated at 184 b.An anti-rotation finger is provided as indicated at 185 b. Wiring of thesensing element of sensor 24 is routed out through a standard connectoras indicated at 186 b. In either option, along with the otherembodiments described herein, magnetic shields can be incorporated inthe sensor housing.

Referring now to FIG. 18, a cross-sectional view of transfer case 170shown in FIG. 16 having a case-mounted magnetic torque sensor packagingdesign 190 in accordance with an embodiment of the present invention isshown. Design 190 also includes the first and second options.

Features of design 190 pursuant to the first option in which a magnetictorque sensor 22 is on the input shaft include the following. Splinesare moved to the right (up to the pump's shoulder) to gain more axialspace for sensor 22 as indicated at 191. This modification is needed toboth of the input and output shafts. The housing of sensor 22 is mountedto the transfer case housing by screws as indicated at 192. Thissupports the sensor housing axially and in a radial manner and functionsas an anti-rotation device. The wiring of the sensing element of sensor22 is routed out through a standard connector as indicated at 193.

Features of design 190 pursuant to the second option in which a magnetictorque sensor 24 is on the output shaft include the following. Thediameter of the output shaft is increased as possible to avoid reductionin the linearity range of sensor 24 as indicated at 194. The housing ofsensor 24 is press fit into the transfer case housing as indicated at195. This supports the sensor housing axially and in a radial manner andfunctions as an anti-rotation device. The wiring of the sensing elementof sensor 24 is routed out through a standard connector as indicated at196. Again, in either option, magnetic shields can be incorporated inthe sensor housing.

Referring now to FIG. 19A, a cross-sectional view of a magnetic torquesensor packaging design 200 in a rear-wheel drive (RWD) axle inaccordance with an embodiment of the present invention is shown. FIG.19B illustrates an enlarged view of the encircled portion of FIG. 19A.

As shown in FIG. 19B, modifications are made to an original designindicated by 202 (top half of drawing) to produce the inventive designindicated by 204 (bottom half of drawing). The modifications to theoriginal design include making the input shaft diameter uniform,locating sensor 22, installing a sensor bobbin indicated at 206.Installing the sensor bobbin includes providing a lube hole indicated at208 and incorporating a spacer indicated at 210 such that the sensorbobbin has anti-rotation capability. The sensor bobbin is a slide-inhousing which is press fitted. Contact points with the housing are closeto the outer race of bearings so that radial movement relative to theshaft is minimized. The modifications further include routing a wirefrom the sensor bobbin. The wire includes a heavy duty cover forprotection against motion and possible damage due to mud, ice, etc. Aconnector is attached to the other end of the wire as indicated at 212for easy installation and removal.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A transfer case assembly comprising: a transfer case shaft having a magnetized region; and a magnetic torque sensor, for detecting torque of the transfer case shaft, mounted on at least one bushing supporting the transfer case shaft.
 2. The assembly of claim 1 further comprising: a transfer case; wherein the sensor is further mounted to the transfer case.
 3. The assembly of claim 1 further comprising: an anti-rotation device connected to the sensor and configured to prevent rotation of the sensor in response to the transfer case shaft rotating.
 4. The assembly of claim 1 wherein: the transfer case shaft includes one of a transfer case input shaft, a transfer case output shaft to rear wheels, a transfer case output shaft to front wheels, and a transfer case output shaft to power takeoff.
 5. The assembly of claim 1 wherein: the sensor includes a sensor housing, wherein the sensor housing includes a channel running therethrough for conveying lubrication to areas adjacent the sensor.
 6. A transmission comprising: a transmission case; a gear having a magnetized region, wherein the gear is one of an idler gear and a transfer gear; and a magnetic torque sensor, for detecting torque transmitted by the gear, mounted to the transmission case.
 7. The transmission of claim 6 wherein: the gear includes a plurality of pieces which together form the gear, wherein one of the pieces includes the magnetized region.
 8. A transmission comprising: a transmission case; an idler shaft; an idler gear and a transfer gear spaced apart from one another about different portions of the idler shaft; wherein the idler shaft includes a magnetized region in a space between the idler gear and the transfer gear; and a magnetic torque sensor, for detecting torque of the idler shaft, mounted on the transmission case adjacent to the magnetized region. 